Posture and body movement measuring system

ABSTRACT

A sensing device is attached to a living subject that includes a first sensors for distinguishing lying, sitting, and standing positions. In another embodiment, sensor data is stored in a storage device as a function of time. Multiple points or multiple intervals of the time dependent data are used to direct a feedback mechanism to provide information or instruction in response to the time dependent output indicating too little activity, too much time with a joint not being moved beyond a specified range of motion, too many motions beyond a specified range of motion, or repetitive activity that can cause repetitive stress injury.

RELATED APPLICATION

[0001] This application is a continuation of provisional U.S. patentapplication 60/271,090, filed Feb. 23, 2001.

FIELD OF THE INVENTION

[0002] This invention generally relates to sensors. More particularly,it relates to a system for making measurements concerning posture,orientation, and movement. Even more particularly, it relates to asystem for measuring posture or repetitive motion and providingfeedback.

BACKGROUND OF THE INVENTION

[0003] The range of motion of a joint of the body may be restricted as aresult of injury. Range of motion can increase with therapy, exercise,and healing. Measurement of range of motion is important in evaluatingthe extent of injury and progress toward healing.

[0004] On the other hand treatment of various injuries may requiretemporary restriction in the range of movement, and devices such ascasts, braces, elastic bandages, and corsets have been used to providesuch temporary restraint. Some of these devices and some ergonomicchairs have also been used to promote a more erect posture.

[0005] Electronic sensors have been developed to measure angles betweenbody segments and to measure range of motion of various joints, asdescribed in commonly assigned U.S. patent application, Ser. No.08/990,912 to Arms, (“the '912 patent application”), filed on Dec. 15,1997, and incorporated herein by reference. The '912 patent applicationdescribes a pair of housings that contain a pair of inclinometer boardassemblies and the cable and plugs for their connection. Theinclinometer board assemblies each include pairs of accelerometersoriented orthogonal to each other, a/d converters, a multiplexer, avoltage regulator, and a microprocessor. The microprocessor computes theangle of each inclinometer housing with respect to the other.

[0006] Commonly assigned U.S. patent application, Ser. No. 09/457,493 toArms, (“the '493 patent application”), filed on Dec. 8, 1999, andincorporated herein by reference discloses an inclinometer that includesthree orthogonal accelerometers and three orthogonal magnetometers usedto measure earth's gravitational and magnetic field vectors from whichpitch, roll, and yaw (compass heading) are calculated. Low pass filtersare provided to minimize effects due to inertial inputs to theaccelerometers that might interfere with accuracy. The invention alsoprovides a digital network to allow multiple devices to be wiredtogether on a single bus, a feature useful for applications, such asposture monitoring.

[0007] Mechanical and electronic sensors have been developed to measurerange of motion, as described in U.S. Pat. No. 4,665,928 to Linial etal. Other devices, such as those described in U.S. Pat. Nos. 4,958,145to Morris, 5,089,808 to Amirdash, and 5,128,655 to Shore use measurementdevices that detect whether an incline angle has been exceeded andprovide an alarm when the user exceeds that prescribed angle.

[0008] Restraint on the extent of movement with the ability to performexercises within a prescribed range is provided in U.S. Pat. No.5,823,975 to Stark, et al. An orthopaedic restraining device is providedwhich provides restraint while permitting a range of exercise duringrehabilitation. A communications device is included to provide feedbackto the prescribing physician so the physician can evaluate the patient'sprogress in regard to the exercise the physician prescribed. The deviceis equipped to summon the patient to perform exercise with a visualalarm or a vibrator, to verify that torque used for the exercise iswithin a prescribed limit, to provide choices of torque and repetitionsfor each exercise, and otherwise give the patient immediate feedbackrespecting exercise. For example, the control program calculates thework or energy exerted by the patient and displays the energy exerted asa percentage of the targeted energy amount.

[0009] U.S. Pat. No. 5,593,431, to Sheldon, “the '431 patent,”determines the physical posture of a patient's body in relation toearth's gravitational field. A device with two or three DCaccelerometers having sensitive axes mounted orthogonally within animplantable housing is adapted to be implanted with the sensitive axesgenerally aligned with the patient's body axes. The activity and bodyposition signals from these sensors may be stored and/or used to monitorand effect the delivery of a therapy to the patient, e.g. by controllingthe pacing rate of a rate responsive pacemaker. The device provides amulti-axis, solid state position and activity sensor operable along atleast two orthogonal axes to distinguish the posture or positionalattitude of the patient at rest and at levels of exercise.

[0010] However, the present inventors found that while the device of the'431 patent can distinguish various lying down positions from each otherand from standing, the device cannot distinguish between various uprightpositions. For example, the device of the '431 patent cannot distinguishsitting from standing positions of the patient. Thus, a better systemfor monitoring is needed that provides improved ability to distinguishposture and activity in upright positions, and this solution is providedby the following invention.

SUMMARY OF THE INVENTION

[0011] It is therefore an object of the present invention to provide adevice that can distinguish lying down, sitting and standing positionsof a user;

[0012] It is a further object of the present invention to provide adevice that distinguishes various postures within the sitting position;

[0013] It is a further object of the present invention to provide adevice that recognizes too much time in a kyphotic posture and promptsthe user to spend more time in lordosis.

[0014] It is a further object of the present invention to provide noticeor instruction indicating too much time in a fixed position or too muchtime with little activity;

[0015] It is a further object of the present invention to provide noticeor instruction indicating repetitive activity that can cause repetitivestress injury;

[0016] It is a feature of the present invention to provide a pluralityof sensors extending on each side of a hip joint to distinguish lying,sitting and standing positions;

[0017] It is a feature of the present invention to provide a pluralityof sensors, a processor, a storage device, and a feedback mechanism,wherein the sensors provide a dc response to detect inactivity or toolittle activity;

[0018] It is an advantage of the present invention that the deviceprovides warning of too much time in a kyphotic posture;

[0019] It is an advantage of the present invention that the deviceprovides warning of too little activity or repetitive activity that cancause repetitive stress injury.

[0020] These and other objects, features, and advantages of theinvention are accomplished by a device for attaching to a livingsubject, comprising a sensor, a processor, and a storage device. Thesensor comprises an acceleration measurement device. Data from thesensor is processed in the processor and stored in the storage devicefor determining when a person is in a sitting position and fordetermining body posture in the sitting position.

[0021] Another aspect of the invention is accomplished by a devicecomprising a sensor, a processor, a storage device, and a feedbacknotifier. Data from the sensor is processed in the processor to providean output. The output is stored in the storage device as a function oftime. Multiple points of the time dependent output stored in the storagedevice are processed in the processor. The processor directs thefeedback notifier to provide information or instruction in response tothe time dependent output indicating too little activity or indicatingrepetitive activity that can cause repetitive stress injury.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The foregoing and other objects, features, and advantages of theinvention will be apparent from the following detailed description ofthe invention, as illustrated in the accompanying drawings, in which:

[0023]FIG. 1 is a block diagram of the sensor unit of the presentinvention;

[0024]FIG. 2a is a three dimensional sensor unit of the presentinvention;

[0025]FIG. 3 is a three dimensional sensor unit of the present inventionshowing rotation around the orthogonal axis including the direction ofthe gravity vector;

[0026]FIG. 4a are equations to used calculate the accelerations and theangular positions of the sensor;

[0027]FIG. 4b show the accelerometers and magnetometers as they areideally positioned along orthogonal axis and rotations around thoseaxes;

[0028]FIG. 4c are equations to used calculate the components of earth'smagnetic field and the rotation of the sensor about the z axis;

[0029]FIGS. 5a and 5 b are flow charts showing two embodiments of thesteps in the program run in the microprocessor of the apparatus;

[0030]FIG. 6 is a three dimensional view of a person using a wireconnected apparatus of the present invention;

[0031]FIG. 7 is a three dimensional view of a person using a wirelessapparatus of the present invention;

[0032]FIG. 8 is a block diagram of a wireless apparatus of the presentinvention; and

[0033]FIG. 9 is a three dimensional view of a person using a wirelessapparatus of the present invention having multiple sensor systems and awrist mounted remote processing unit.

DETAILED DESCRIPTION OF THE INVENTION

[0034] The present inventors recognized that available accelerometerbased posture monitors could not distinguish between lying down and eachupright position of sitting and standing. The '431 patent, for example,distinguishes among several lying down positions but has no mechanism todistinguish sitting from standing. In addition, the present inventorsrecognized that physical discomfort and medical problems arising fromposture and repetitive movements can be prevented with appropriatecharacterization and feedback.. They recognized a common solution for avariety of problems, such as (a) extended time in a single position; (b)extended time sitting in a slouching posture (kyphosis) as opposed tositting in an erect posture (lordosis); and (c) repetitive stressfulmovements, such as may be found on some manufacturing lines, whiletyping for an extended period of time without proper wrist support, orwhile working all day at a job lifting boxes.

[0035] The present inventors designed a miniature electronic device thatrecords position and posture within that position data over time, sensesthe circumstances that could lead to physical problems by analysingposition and posture data over time, and signals the user to take actionto avoid injury. The same equipment can also be used during physicaltherapy to monitor movements and exercises to ensure that a prescribedrange of motion is not exceeded and to encourage proper performance ofprescribed exercises. It can also be used to analyse movement duringparticipation in physical activity, such as a sport involving a swing,to improve performance.

[0036] In one embodiment, the present invention networks a pair ofangular position sensors, one on each side of the hip joint, todistinguish lying down, sitting, and standing positions. In anotherembodiment, the present invention repeatedly records position and/orposture data over time. Feedback is provided when a condition is met,such as position remains constant for too long a period of time orposture is kyphotic for too long a period of time. Feedback can also beprovided if a repetitive stressful movement is repeated too many timesor if a desired range of motion limit is exceeded too many times.Feedback can take the form of a vibration or an audible signal.

[0037] The present inventors recognized that there are three componentsto human energy expenditure in non-exercising subjects; basal metabolicrate (BMR), thermic effect of food (TEF) and non-exercise activitythermogenesis (NEAT). BMR is the rate at which energy is expended whenan individual is laying down at rest in the postabsorptive state. Insedentary individuals it accounts for approximately 60% of total dailyenergy expenditure (TDEE) and is highly predicted by lean body masswithin and across species, as described in a paper “Avian basalmetabolic rates: their association with body composition and energyexpenditure in nature,” by S. Daan, D. Masman, and A. Groenewold, Am JPhysiol, 1990;259(2 Pt 2):R333-40, and in a paper “Some consequences ofbody size,” by L. E. Ford, Am J Physiol, 1984;247(4 Pt 2):H495-507. TEFis the increase in energy expenditure associated with the digestion,absorption, and storage of food and accounts for approximately 10% ofTDEE. Several investigators believe TEF to represent a fixed proportionof TDEE, as described in a paper, “Human energy expenditure in affluentsocieties: an analysis of 574 doubly-labeled water measurements.” by A.E. Black, W. A. Coward, A. M. Prentice, and T. J. Cole, Eur J Clin Nutr,1996;50(2):72-92 and to be the invariant energy cost of converting foodto metabolic fuels, as described in a paper, “Meal size and thermicresponse to food in male subjects as a function of maximum aerobiccapacity,” by J. O Hill, S. B. Heymsfield, C. D. McMannus, and M.DiGirolamo, Metabolism, 1984;33(8):743-9, and in a paper, “Thermiceffect of food in lean and obese men,” by D. A. Alessio, E C Kavle, M AMozzoli, et al., J Clin Invest, 1988;81(6):1781-9 whereas others proposethat TEF is actively regulated in response to changing food intake, asdescribed in a paper, “Independent effects of obesity and insulinresistance on postprandial thermogenesis in men,” by K R Segal J Albu, AChun, A Edano, B Legaspi, and F X Pi-Sunyer, J Clin Invest.1992;89(3):824-33.

[0038] NEAT is the thermogenesis that accompanies physical activitiesother than volitional exercise, such as the activities of daily living,such as sitting, standing and walking, body movement plus fidgeting,spontaneous muscle contraction, and maintaining posture when notrecumbent. It accounts for approximately 30% of TDEE.

[0039] In one study published in a paper, “Assessment of the heart-ratemethod for determining energy expenditure in man, using a whole-bodycalorimeter,” by M. J. Dauncey and W. P. James, published in Br J Nutr,1979; 42(1): 1-13, the energy expenditure associated with lying, sittingand standing was measured in eight men confined to a room calorimeter.Total energy expenditure increased by 10% when seated compared to lyingand by 36% when standing compared to lying. Furthermore, when thesesubjects were allowed to make voluntary movements to resemble fidgeting,energy expenditure increased further by 26±(SD) 1% in the lyingposition, 17±16% in the sitting position, and by 27±14% in the standingposition. This experiment and others consistently demonstrate that lowgrade activities such as walking at ≈2 mph or cycling at 50W isassociated with 2-3 fold increases in energy expenditure (7,9,10).Furthermore, the number of hours spent per day performing theseactivities can be added up so that the contribution of NEAT activitiesto total daily energy expenditure in free living, sedentary subjects canbe clarified (FIG. 1). Thus, NEAT not only accounts for many hours ineach day (in fact, in sedentary individuals,all hours spent awake, notresting and not eating) but the thermogenesis associated with each ofthese components is sufficiently great that NEAT has the potential tocontribute significantly to total energy expenditure. The substantialmajority of NEAT is accounted for by identifiable components such asbody movement, sitting, standing and walking; fidgeting (small,non-purposeful distal limb movements) also contribute to NEAT.

[0040] A paper, “Role of nonexercise activity thermogenesis inresistance to fat gain in humans,” by J. A. Levine, N. L. Eberhardt, andM. D. Jensen, published in Science, 1999; 283(5399):212-4, concludesthat increases in NEAT predict resistance to fat gain with over-feeding.However, investigations into the mechanism of this effect are hamperedby the limited information regarding the components of NEAT infree-living subjects.

[0041] The present inventors recognized that there is a large potentialmarket for “smart” wearable instruments capable of comprehensiverecording of human activity, body position, and energy expenditure isavailable. For example, approximately 800 obese patients are treatedeach year by the nutrition clinic of the Mayo Clinic. In the presentinvention, such patients would be allowed to keep their monitors of thepresent invention, and an infrastructure for remote data access over theinternet over a secure server would allow clinicians, therapists, andpersonal trainers to improve their knowledge of each patient's activitylevel and compliance with treatment regimen.

[0042] Previously existing wearable monitors based on dynamicacceleration have not been able measure NEAT, since their outputs dropto zero when the subject stops moving. Heart rate monitors cannotmeasure NEAT reliably, since they also do not reflect the body'sposition or posture. However, the present inventors have providedinstrumentation to overcome this difficulty. The instrument developed bythe present inventors provides body position and posture, and providesinformation regarding slow movements of the body that can be correlatedwith NEAT.

[0043] The present inventors designed a comprehensive instrument tomeasure human activity and body position and to detect the contributionsof sitting, standing, walking and fidgeting thermogenesis to NEAT. Theinstrument distinguishes and measures bouts of exercise as well ascontributions from normal sedentary life. The instrument providesfeedback to the wearer. This device can thus be used to modify humanactivities, and therefore has the potential to affect an individual'sweight and posture.

[0044] A preliminary version of the device with a single sensor unit forplacement on one body segment was evaluated in a paper, “Evaluation ofBiofeedback Device in Reducing Pain and Improving Function ofIndividuals with Low Back Pain,” by Krag, M. H., Fox, J. R., andMcDonald, L. P.: published in Rehabilitation Society of N. America,Pittsburgh, Pa., 1997. The authors showed that wearing this device canresult in more erect trunk postures which may result in reduced loads onthe supporting muscles of the spine. Results of tests with the devicewere described in a paper, “Oh, My Aching Back”, by Wolkomir, R.,published in Smithsonian Magazine, pages 38-48, August, 1998.

[0045] The measurement of spinal curvature may prove useful, especiallyin applications where prolonged static standing and/or sitting may beencountered. Various scientific studies have documented that a prolongedseated posture, especially without proper lower back support, isdetrimental to those who suffer from low back pain. Devices to monitorcurvature of the spine during prolonged sitting have been developed.Such a “lordosimeter” typically includes a thin, flexible, polymeric ormetallic strip or strips embedded within or covered by compliantmaterials. It may be placed comfortably along the spine using elasticstraps. The thin, flexible strip typically includes one or more straingauges such as bonded foil types, piezo-resistive, inductive,capacitive, or fiber optic. The strain gauge converts the bending of thestrip as posture changes into an electrical signal indicative of spinalcurvature. An example of these fiber optic curvature sensing devices isdescribed in U.S. Pat. No. 5,321,257, incorporated herein by reference,and the devices are available from Measurand, Inc., Fredericton, NB,Canada.

[0046] In the present invention, output data of the lordosimeterproviding spinal curvature is logged continually. The unit is programmedto provide feedback to the user if the user remains in a poor posturefor too long a time. The unit is also programmed to warn the user if heor she remains in any static position for too long a time. Thus, theunit encourages the user to move around frequently and to avoid poorposture. The feedback can enhance the user's awareness of his or herposture. In addition, information about trunk inclination andorientation from measurements taken over a period of time can helpdetermine what posture or movements are related to back pain.

[0047] In addition to monitoring position and posture, with biofeedback,wearable instruments could also enhance patient compliance withprescribed rehabilitation/exercise programs after a back injury or aspine surgery or during rehabilitation of injuries to other parts of thebody.

[0048] A paper, “The Biomechanics of Low Back Injury: Implications onCurrent Practice in Industry and the Clinic,” by S. M. McGill, publishedin J. Biomechanics, Vol. 30, No. 5, pp. 465-475, 1997, suggests thatchanging the body's position can alleviate joint pain and joint problemsassociated with overuse. Overuse injuries have risen in recent years,partly due to the increased time spent using computers, where theoperator may infrequently change position and posture at the keyboard,as described in “OSHA—Its Role in the American Workplace” by R.Ferrante, executive producer, reported on National Public Radio byRobert Edwards, NPR's morning edition, Apr. 4, 1996.

[0049] The instrument developed by the present inventors is a wearabletrainer or coach or personal tamaguchi device that reminds its owner tochange position, get up, walk, stretch, or vary activities that overusea joint. The instrument logs data concerning the user's time history ofactivity, position, posture, movements, and the device can test forcompliance with programmed goals. A built-in display may provide cuesand/or a composite health score based on the recorded data. Thesecapabilities could not only benefit those persons who are recoveringfrom an injury, they could also prevent overuse related injuries.

[0050] In addition, the data gathered from the device of the presentinvention would be valuable to researchers and to companies who employindividuals who may be at risk for overuse injuries, including packagehandlers, meat packers, movers, athletes, computer users, elderlypersons, etc. Wearable activity, position, and posture instruments couldbe also be used to record patient compliance with prescribed exerciseand could proactively prompt the patient to perform prescribedactivities to result in improved outcomes.

[0051] MicroStrain, Inc. designed and has long been marketing wearabledataloggers for tracking trunk inclination with biofeedback through avibrating pager enclosure, termed the Virtual Corset (Photo 1). Thesedevices run for approximately six weeks using a single AA size battery.Data are recorded in an on-board non-volatile memory and can bedownloaded via a connection to the serial port of a personal computer.Inclination is measured using a triaxial array of orthogonal static &dynamic response accelerometers. Preferably the inclinometer hascapability to measure 360 degrees about at least one axis, as providedin a sensor available from Microstrain, Inc. called FAS-A. Even morepreferably the inclinometer has capability to measure 360 degrees abouttwo axes, which can be accomplished by providing three orthogonalaccelerometers for each device attached to a body segment. For example,for measurement's of a person's torso, such a device providesmeasurement of flexion/extension (forward and backward bending) andlateral bending (sideways bending).

[0052] To also measure rotation of the body about an axis along thegravity vector one can also include three orthogonal magnetometers alongwith the three orthogonal accelerometers, as described in a paper, “AMiniature, Sourceless, Networked, Solid State Orientation Module”, byTownsend, C. P., Guzik, D. C., Arms, S. W., published in the 9^(th)International Conference on Adaptive Structures & Tech. (ICAST),Cambridge, Mass., October 1998, (“the ICAST paper”), and in a patentapplication 1024-045. This device is is available from Microstrain, Inc.and is called 3DM.

[0053] In order to detect and distinguish body position, such asstanding, sitting, and lying down, the present inventors found that asecond sensor unit was needed. The present invention networks a pair ofangular position sensors, one on each side of the hip joint, todistinguish the three positions. It uses a networked array of angularposition sensors termed 3DM's, as described in commonly assigned U.S.patent application Ser. No. 09/457,493, incorporated herein byreference. The idea of networking sensors is also mentioned in the abovementioned ICAST paper by Towsend.

[0054] To also measure angular rotation about an axis, including angularrotation of a body and twist of a joint about the axis, the presentinventors found that a second sensor unit was needed, one on each sideof the joint. The sensor unit preferably provides 3 accelerometers andthree magnetometers, such as the 3DM device of Microstrain, Inc., asdescribed in the ICAST paper by Townsend. The joint can be the ankle,the knee, the hip, spine, neck, shoulder, elbow, or wrist. For example,for measuring axial rotation or twisting of the spine in a standingposture, one 3DM is mounted to the lower spine around the pelvis and theother is mounted to the upper body around the chest.

[0055] It is worth noting that for a subject in a lying down postureaxial rotation of the spine can be measured with gravity referenceddevices alone, without magnetometers, but gravity referenced devicescannot be used for such measurements when in a standing posture.

[0056] The present invention links a triad of dynamic and staticresponse accelerometers and a triad of magnetometers attached to a thighand similar triads attached to torso. The magnetometers provide absoluterotational position about an axis coincident with Earth's gravity vector(compass heading, or yaw). Network capability is provided by an RS-485connection between the sensors. The apparatus of the invention wastested on subjects who were standing, sitting, and lying, and theresults show that accelerometer outputs from sensors on thigh and torsowere easily able to distinguish the three positions, as shown inTable 1. TABLE 1 Voltage outputs from inclinometers applied to the thighand torso to detect standing, sitting and lying in three adults. Dataare the mean of ten repetitions ± SD. Subject 1 1 2 2 3 3 Thigh TorsoThigh Torso Thigh Torso Standing 0.78 ± 0.88 ± 0.84 ± 0.91 ± 0.80 ± 0.98± 0.01 0.03 0.01 0.04 0.01 0.03 Sitting 4.00 ± 0.93 ± 3.94 ± 0.78 ± 3.87± 0.78 ± 0.04 0.05 0.03 0.02 0.04 0.05 Lying 3.91 ± 3.92 ± 4.1 ± 3.87 ±3.77 ± 4.12 ± 0.03 0.02 0.04 0.03 0.04 0.03

[0057] The data shows a large difference in the output on thigh andtorso for a sitting subject and no significant difference between thighand torso sensors for both standing and lying subjects. However,standing and lying are distinguished by the large difference inmagnitude of the output for these positions. Thus, all three positionsare distinguished by providing linked sensors, one on the torso and asecond on the thigh.

[0058] The data shows that body position can be measured reliably usingonly accelerometers to perform the sagittal plane body positionmeasurement; no magnetometers were needed to distinguish standing,sitting, and lying. This simplification allows elimination of orthogonalmagnetometers, reducing system complexity, power demands, and potentialerrors associated associated with local variations in Earth'sgeomagnetic field. The magnetometers are only needed for measuringrotation or twist about an axis coincident with the gravity vector. Theycan be omitted to reduce cost complexity and power when measurementalong such axis is not needed, as for the device to merely distinguishstanding, sitting, and lying.

[0059] Preferably the accelerometers have a DC response, enablingmeasurement of steady state accelerations such as the gravity vector andinclination respect to the gravity vector. The same accelerometers canalso be used to determine linear velocity by integrating measuredacceleration over time. A block diagram of sensor system unit 20 a,shown in FIG. 1, includes inclinometer 22. Two or three orthogonal DCresponse accelerometers can be used to form the sensing portion ofinclinometer 22. Accelerometers 23 a, 23 b, and 23 c, shown in FIG. 2a,such as the ADXL202 (Analog Devices, Norwood, Mass.) have a DC response,offer very small package size and use extremely low power. The output ofeach accelerometer 23 a, 23 b, 23 c is fed separately to low pass filter24. The cutoff frequency of low pass filter 24 is typically set to ½ thesampling frequency for antialiasing. The output of low pass filter 24 issent to the analog input of flash based microprocessor 26 (16F877 or16C877 from Microchip Technology, Chandler, Ariz.) which includes analogto digital (A/D) converter 28. A flash based microprocessor has on boardflash memory for storing a program that will be run on themicroprocessor. This on board flash memory plus additional non-volatileflash memory chip 30 are advantageous in that they allow for fieldreprogramming of the firmware without requiring replacement of themicroprocessor chip. A crystal oscillator (not shown) is included withmicroprocessor 26 to control the timing of the microprocessor. Time isthen determined in microprocessor 26.

[0060] In the embodiment of FIG. 1, all the requisite electronics,power, and packaging are contained in one sensor system 20 a. Sensorsystem 20 a also includes signal conditioning electronics 32,biofeedback mechanism 33 for providing feedback to the user,communications circuit 34 a, internet interface 34 b, power supply 35,and input button 36. Sensor system 20 a can also include magnetometersor other sensors 38.

[0061] Microprocessor 26 samples the three accelerometers 23 a, 23 b, 23c (FIG. 2a) within inclinometer 22 at a sampling rate, such as 100 Hz.The data that was low pass filtered in hardware filter 24 will also befiltered in software run on microprocessor 26 using an Infinite ImpulseResponse (IIR) low pass digital filter that is formed in software to runon microprocessor 26. The IIR software filter allows very low cutofffrequencies to be achieved without using large components that would berequired in hardware filters; and the filter can be made programmable bythe user. Using both hardware and software filters provides additionalnoise reduction. Hardware low pass filter 24 also serves as anantialiasing filter, which is a filter that limits the frequency contentof the sensor signal to a maximum frequency that is half the sample rate(100 Hz).

[0062] The device of the present invention employs at least oneaccelerometer based inclinometer 22 to measure the orientation of thewearer's body segments relative to earth's gravitational vector. In thepreferred embodiment, accelerometers with a DC response are used tocalculate angle so that information about the user in a quiescent statecan be obtained and stored. If a triad of accelerometers 23 a, 23 b, 23c are used than an angle from +/−180 degrees can be measured on one axisrelative to the gravity vector, and an angle range of +/−70 degrees canbe measured on the other axis orthogonal to the first axis relative tothe gravity vector, as shown in FIG. 3. The device uses microprocessor26 that samples data from accelerometers 23 a, 23 b, 23 c and calculatesthe angles θ_(x) and θ_(y) from equations 41-45 in FIG. 4a. Offset andgain calibration coefficients a_(xgain), a_(ygain), a_(zgain) used inequations 41-43 are stored in nonvolatile memory chip 30 on system 20 a.Angles θ_(x) and θ_(y) so calculated are also stored in nonvolatilememory 30. Sampling is typically done at a frequency of 100 Hz but othersample frequencies can be programmed. The advantage of higher samplingfrequency is that information about faster motions can be captured. Theadvantage of lower sampling frequency is that less data storage isneeded.

[0063] a_(x), a_(y) and a_(z) are calculated from the measuredaccelerometer sensor values along each axis, x, y, z, using equations41, 42, 43, as shown in FIG. 4b. In the equation to calculate theacceleration along the x axis, ax, a_(xraw) is the raw voltage readingfrom the x axis accelerometer. a_(xoffset) is the offset coeficient toadjust the accelerometer for initial offset errors. a_(xgain) is acoefficient to convert a_(xraw) to a true acceleration reading.A_(xgain) has units of g's per volt. Similar equations provide the yaxis acceleration, a_(y), and the z axis acceleration, a_(z).

[0064] Rotations about the x and y axes are calculated in equations 44and 45 by combining the accelerations calculated in equations 41, 42,and 43. Solid state accelerometers are well known in the art.

[0065] To measure rotations about the Z axis, magnetometers arerequired. The three orthogonal components of earth's magnetic fieldm_(x), m_(y) and m_(z) are calculated from the measured values frommagnetometers 38 a, 38 b, and 38 c using using equations 71, 72, 73, asshown in FIG. 4b′. In the equation to calculate the magnetic field alongthe x axis, mx, m_(xraw) is the raw voltage reading from the x axismagnetometer. m_(xoffset) is the offset coeficient to adjust themagnetometer for initial offset errors. m_(xgain) has units of Gauss pervolt. Similar equations provide the my and mz values. From m_(x), m_(y),and m_(z), θ_(z) can be calculated from equations 74, 75, 76, and 77shown in FIG. 4c.

[0066] Accelerometers 23 a, 23 b, 23 c are also used to calculate linearvelocity. To determine the linear velocity the output of the hardwarelow pass filter is sampled at a rate of 100 Hz. To measure linearvelocity, the portion of acceleration due to the gravity vector iseliminated using a high pass digital filter, which eliminatesaccelerations that remain constant. The high pass digital filtering isperformed by microprocessor 26 using software stored on nonvolatilememory 30. The gravity vector is fixed at g, and therefore has afrequency of zero, so a high pass filter eliminates the gravity portionof the acceleration signal. As described herein above, the accelerometerdata is scaled for offsets and gains and the magnitude of the resultantacceleration vector components a_(x), a_(y) and a_(z) are computed, asdescribed in equations 41, 42, and 43. While a uniform velocity cannotbe measured with accelerometers, the time integral of the accelerationis computed using a digital numerical integration step to obtain thechange in linear velocity vector resulting from acceleration.

[0067] The results of the inclination and velocity calculations arestored in non-volatile flash memory 30 for each point in time as shownin the flow chart of FIG. 5 at box 110. This non-volatile memory chip 30has the capability to store up to 4 megabytes of data on a singleintegrated circuit. The format of data storage in non-volatile flashmemory 30 is programmable.

[0068] As an alternative to storing inclination and velocity at eachpoint in time, the format of data storage can be programmed so theaverage of the inclination and velocity data over a programmable timeperiod is stored at each interval of time, as shown in the flow chart ofFIG. 5a at box 111. As another alternative, inclination angles andvelocities can be segmented into bins and data accumulated in each binas data is obtained at each point in time, as also shown at box 111.This provides histograms of the frequency of velocity and inclinationangles over each time period. In this case, however, the sequentialaspect of the information is removed.

[0069] Sensor system 20 a can be located on one body segment, such asthe lower trunk or the upper trunk, as shown in FIG. 6. A pair of sensormodule units 20 a, 20 b can also be provided, one on each side of ajoint, such as the hip joint. The difference between measurements ofpair of sensor systems, 20 a, 20 b can be provided to detect angularposition of the hip joint. Pairs of sensor systems 20 a, 20 b may beconnected by wired 46 and connectors 48 a, 48 b or may use wirelesscommunications, such as RF link 34 a and antenna 49. The differencebetween the measurements of sensor systems 20 a and 20 b can be used todistinguish standing from sitting positions.

[0070] Pair of sensor systems, 20 a, 20 b′ can be provided to detectangular position of other joints in addition to or instead of the hipjoint or to measure how that joint angle varies with time by taking thedifference in the outputs of two sensor systems 20 a, 20 b′ one on eachside of the joint, as shown in FIG. 6 for a knee joint.

[0071] Where two or more sensor systems 20 a, 20 b or 20 b′ areprovided, sensor systems 20 b, 20 b′ need not have all the components ofsensor system 20 a, as shown in FIG. 1. Input button 36 to biofeedbackmechanism 33 and internet interace 34 b can be eliminated from slavesensor systems 20 b, 20 b′ since those functions can be provided bycomponents in master sensor system 20 a.

[0072] Inclinometers based on DC response accelerometers such as theADXL202 (Analog Devices, Norwood Mass.) have been described in commonlyassigned U.S. patent application Ser. No. 08/990,912, docket number1024-040, herein by reference, and may be purchased commercially asFAS-A from MicroStrain, Inc., Burlington, Vt.

[0073] Sensors 20 a preferably include accelerometer based inclinometers22. They can also include magnetometers 38 to provide orientation aroundthe gravity vector and to provide a complete orientation sensor.Orientation measurement devices that include magnetometers, such as the3DM device of MicroStrain Inc., typically use both magnetometers andinclinometers to compute rotations coincident with the gravity vector.Such devices have been described in commonly assigned copending patentapplication Ser. No. 09/457,493, docket number 1024-045.

[0074] Power may be supplied with battery power supply 35 that can be abattery, such as a miniature camera battery, and this battery can berechargeable.

[0075] Biofeedback mechanism 33 can include a visual display capable ofproviding text or images or it can include a device that provides anaudible signal, such as a piezoelectric buzzer, visual display, or avibrator such as an electromagnetic shaker.

[0076] While biofeedback mechanism 33 can be included within sensorsystem 20 a, as shown in FIG. 1, biofeedback mechanism 33 can also beprovided on a separate remote processing unit 39 that is used along withsensor systems 20 a, 20 b, as shown in FIG. 6. This separate remoteprocessing unit 39 may be strapped to the user's waist, as shown in FIG.6 and 7, or it can mounted to another part of the user's body, such asthe user's wrist, similar to a wristwatch, as shown in FIG. 9.

[0077] Feedback mechanism 33 and remote processing unit 39 can alsoprovide for communication from a clinician treating patient as well asfeedback based on the data collected by sensor system 20 a as determinedby the software program stored on nonvolatile memory 30 and run onmicroprocessor 26. Feedback mechanism 33 may also be combined with inputunit 36, such as a single button or a keyboard, for the user to provideadditional communication back to the clinician, as shown in FIG. 1 andin FIG. 2b. Thus, in addition to collecting data about the user'smovement and posture for use by the internal program and fortransmitting to the clinician, and for providing feedback, instructions,encouragement, or other display to the user, feedback mechanism 33 andremote processing unit 39 can also allow the user to let the clinicianknow when the user experiences pain or to communicate other information.

[0078] Data transmission between simplified sensor system 20 b andremote processing unit can be accomplished by hard wiring the two, asshown in FIG. 6. Preferably communication between simplified sensorsystem 20 b′ and remote processing unit 39′ would be wireless, as shownin FIGS. 7 and 8a-8 c. In either the wired or wireless embodiments, eachsensor system 20 b′ can be simplified somewhat to eliminate biofeedbackmechanism 33, nonvolatile memory 30, input unit 36, and internetinterface 34 b since these can be provided in remote processing unit39′. Simplified sensor system 20 b′ would now include measurementsensors, such as inclinometer 22, signal conditioners 32, filters 24,a/d converter 28, microprocessor 26, power supply 35 and communicationmechanism 34 a. Microprocessor 26 is provided with each sensor system 20a′ so data is reduced to inclination or joint angle as a function oftime and so the time dependent inclination or angle data is transmittedin digital form.

[0079] The wireless version of communication mechanism 34 a of FIG. 1that is shown in FIG. 8a includes RF transmitter 50 (available fromMicroStrain, Inc. Burlington, Vt.) for transmitting data from sensorsystem 20 b′ to remote processing unit 39 shown in FIG. 8b through RFtransceiver 52 for remote data processing there in microprocessor 54.Remote processing unit 39 also includes data logging in non-volatilememory 56, biofeedback through biofeedback mechanism 58, and display 60,enabling the user to receive information, while power is provided toeach of these components by power supply 62. Power supply 62 can be asmall watch battery. Further transmission from remote processing unit39′ to host PC 64 is provided through RF transceiver 66, as shown inFIG. 8c.

[0080] Alternatively, RF transmitter 50 and transceivers 52 and 66 canbe an infrared digital access (IRDA) link. In cases where line of sightis not practical then RF links would be employed. While wrist borne isconvenient, remote processing unit 39′ need not be wrist-borne; it canalso be attached to the waist or to another convenient part of the body.It can also be held in a pocket, or strapped to another body part or itcan also be hand held.

[0081] Wireless communication facilitates free range of motion, permitsgreater ease of use, enhances patient acceptance, has less potential forbreakage due to lead wire fatigue, and is easier to integrate intogarments such as bras or other unobtrusive strap-like apparel. Miniaturewireless devices are available which contain the requisite electronicsfor digital transmission of data using narrow band surface acoustic wave(SAW) or crystal oscillators, such as StrainLink™ modules available fromMicroStrain, Inc.

[0082] Inclination data can be transmitted along with error checkingfrom two separate sensors without RF collisions by using correctlyconfigured Strainlink™ modules operating at different frequencytransmission bands (such as 916 MHz and 303.825 MHz). Thus, data from asingle pair of sensor systems 20 a′, 20 b′, formed of dual or triaxialaccelerometers and mounted on adjacent limb segments can be used asshown in FIGS. 1 and 7. Alternatively, a plurality of sensor systems 20b′ can be simultaneously transmitted to remote processing unit 39,remotely processed there, and further transmitted to provide range ofmotion data to the clinician, as shown in FIG. 9.

[0083] Software capable of allowing remote re-programming of pre-setparameters is provided in non-volatile memory 56 of remote processingunit 39 for processing in microprocessor 54 in this unit. This is thesame software described herein above that would otherwise be providedfor each individual sensor system 20 a, or 20 a′ for each pair of sensorsystems, 20 a, 20 b or 20 a′, 20 b′ provided across a joint.

[0084] Sensor module system 20 a, or 20 a′ or host system 64 could alsoincorporate a wired or wireless transmission system to allow for datatransmission back to the clinicians′ office without requiring the wearerto return to the office. In one embodiment the data is transmitted toreceiver 66 and associated PC host 64 that is located in the patients′house. When all the data for the day has been acquired, host 64 woulddial into the clinician's office and send the information over a modemor internet connection, as shown in FIG. 8C. This would all betransparent to the user. This would reduce the costs of administeringthe service significantly, by reducing the amount of time the clinicianwould have to see the patient. This would also allow for the clinicianto view more data than would be possible if requiring the patient tocome to the office could only retrieve data.

[0085] It is advantageous to implement the capability for the device totransfer data over the internet. With this capability it is possible forthe patient to transfer data to the clinician's office without requiringthe physical presence of the patient. It also would allow for the deviceto be updated and change parameter's, such as allowable range of motionbefore a warning is triggered.

[0086] Remote processing unit 39′ includes display 56 that may providesimple text commands. Display 56 could also provide graphicalrepresentations of people doing various movements to communicate thedesired information or instruction to the user. The graphical displayallows for the display of a score, helps teach good posture, and helpsthe user through exercises. Remote processing unit 39′ can also be usedto perform mathematical computation of joint angles. It can be the unitthat uses the data to conclude that a preset limit to range of motionhad been exceeded too many times, that the subject has been toosedentary. Once the data from sensor system 20 a, 20 a′, 20 b, 20 b′ hasbeen received and interpreted by wrist-borne remote processing unit 39this unit could also provide feedback to the user using a vibrational,audible, or visual signal.

[0087] When preset or remotely programmed conditions are detected, suchas movement extending beyond a preset range of motion, the user isprovided feedback as shown in box 113 of the flow chart in FIG. 5a.Feedback can be negative feedback seeking to halt or reverse thatmotion. When the user performs a requested task well or indicatesimprovement in compliance with program requests, the user may beprovided positive feedback, such as a higher “health” score. Theseconditions, programs, displays, and interactions can all be programmedby the clinician (at the office or remotely) depending on the user'sbehavior or the clinician's expert assessment of the user's progress.

[0088] In addition to providing a biofeedback signal, it is advantageousto continually save information about the user's range of motion, whichmay be changing with time. This allows the clinician to evaluaterehabilitation progress. In addition, stored information provides avaluable research tool to study how movement or lack of movement maycorrelate with low back pain, cardiac ailments, dietary modifications,pharmacological treatments, and postural control.

[0089] Data can be saved as inclination angle at each time. It can besaved more compactly in histograms; each histogram's sum represents thetotal count of trunk inclination angles measured at the programmedsample rate (binning frequency). While more data can be stored inhistogram format, the association with time of each individual datapoint and the time sequence is lost. Binned data are very useful inreducing the datalogger's requisite memory; once collected, thesehistogram data are easily downloaded over the serial port ofmicroprocessor 26 on sensor system 20 a or microprocessor 54 withinremote processing unit 39′ for analysis. The device logs inclination in1 degree increments (factory set, but may be programmed) over ±180 inthe flexion extension axis and ±70 degrees on the lateral bending axis.The sample rate for data collection is termed the binning frequency; asdata is collected, the unit builds a histogram of inclination overspecified time intervals (bin save interval) and then saves thishistogram to memory. The process is repeated until the device is turnedoff or the memory capacity is reached. The data and programmingparameters are saved in non-volatile memory, and will not be lost in theevent of power down or low battery capacity.

[0090] The bin save interval can be programmed for any amount of time,but longer intervals provide lower resolution of the wearer's activity.For example, if the bin save interval were set at one hour, at the endof the day there would be 24 histograms showing the wearer's trunkinclination angle at the period of the binning frequency. This wouldshow a histogram of inclination for each hour over the course of a day.If the bin save interval were set at 12 hours, at the end of a day therewould be only 2 histograms of inclination. Longer bin save intervals useless memory than shorter bin save intervals, but longer bin saveintervals provide less information about daily activities. The advantageof binning over saving data sequentially over time is that binning usesless memory.

[0091] Binned data has been collected and presented in a paper,“Evaluation of Biofeedback Device in Reducing Pain and ImprovingFunction of Individuals with Low Back Pain,” by M. H. Krag, J. R. Fox,and L. P. McDonald, Rehabilitation Society of N. America, Pittsburgh,Pa., 1997.

[0092] Binning of data saves memory but the sequential recording ofevents is lost with binning. This is a limitatioon when repetitivemotions of activities need to be recorded or when continuous exposure toa single posture or position or vibration occurs. In these cases theproduct of position and time is a measure of a person's exposure to thatposition. The repeated pattern of movement may also be important toasess exposure in a workplace environment. This analysis requires thatpostural and motion measurements be recorded sequentially and along withthe time of the measurement. FIG. 5a provides a flow chart detailingthis sequential recording of data.

[0093] The user can record events (such as the presence of pain) withinput button 36 which can be included either in sensor system 20 a or onremote processing unit 39. Button 36 can also be on wrist-borne remoteprocessing unit 39′ to conveniently allow the wearer to provide thisinput when experiencing pain. When button 36 is pressed, the time may belogged and stored in the system, along with other data, such as time ofday, inclination, orientation, heart rate, blood pressure, etc. Thissystem of measurements and data communications will allow the clinicianto gain insight into the pain the user has experienced along with achronological history of the ranges of motion and activities the patientexperiences leading up to the onset of pain. If a correlation can bedetermined, the clinician can program the biofeedback to try todiscourage the wearer from performing events that led to pain. Thisfeature may be especially important for back pain sufferers, since theyoften experience pain well after the physical activities that may havecaused the pain.

[0094] Accelerometers 23 a, 23 b, 23 c used to sense inclination anglecan also be used to sense the vibration that the user is experiencing.For example, for a worker using a jack hammer or a chain saw, the deviceof the present invention will measure the vibration, log the vibrationexposure dose received by the worker over time, and then give feedbackif this worker receives more vibration dose than a preset vibrationexposure dose. The frequency and magnitude of the vibrations isdetermined by calculating fast fourier transforms (FFT) of theacceleration data coming from the accelerometers or logged in memory.This FFT data is logged, and feedback can be provided based on themagnitude, frequency, and time history of the calculated vibrations. Itis well known how to do a FFT, and the algorithm to transform a timedomain signal to a frequency domain signal is also well known.

[0095] Variables can be initialized and initial readings can also betared out as shown in box 102 of FIG. 5a. The sensor is initialized to aknown angle, such as zero, before the first measurement is taken. Thisis especially useful for postural control applications, since the usermay tare the device at a desired position, regardless of slightvariations that may result from various mountings to the wearers′ body.

[0096] The wearer places a miniature sensor module package 20 a, 20 a′in a small pouch located in their bra, or bra-like device on the chestor on the wrist. This miniature sensor module package 20 a, 20 a′contains inclinometer 22 with vibratory biofeedback capability. The userthen stands in front of a mirror to better view his or her own posture.Once a desirable physical appearance or a comfortable posture, or both,is achieved, the user initializes or “tares” the unit. When the userexceeds a pre-programmed inclination angle (in this case, say 2degrees), the user experiences vibratory or other feedback from thefeedback mechanism 33 as shown in the flow chart in box 113 of FIG. 5a.If the subject is undergoing vigorous physical range of motions (such assit-ups or other flexion type exercise), the unit interprets thesepatterns and does not provide feedback so as not to annoy the wearerduring exercise.

[0097] In addition to magnetometers, the present invention also providesfor data to be collected and monitored from other sensors 38 such asforce measurement sensors, temperature, electrocardiogram (ECG/EKG),electromyograph (EMG), and lumbar curvature, as shown in FIG. 1.

[0098] While several embodiments of the invention, together withmodifications thereof, have been described in detail herein andillustrated in the accompanying drawings, it will be evident thatvarious further modifications are possible without departing from thescope of the invention. Nothing in the above specification is intendedto limit the invention more narrowly than the appended claims. Theexamples given are intended only to be illustrative rather thanexclusive.

What is claimed is:
 1. A device for attaching to a living subject,comprising a first sensor, a second sensor, a processor, and a storagedevice, said a first sensor for attaching to a first body segment abovea hip joint, said second sensor for attaching to a second body segmentbelow the hip joint, wherein said first sensor and said second sensoreach comprise an inclination measuring device, wherein data from saidfirst sensor and from said second sensor is processed in said processorand stored in said storage device for distinguishing lying, sitting, andstanding positions.
 2. A device as recited in claim 1, wherein saidinclination measuring device comprises a solid state device.
 3. A deviceas recited in claim 2, wherein said inclination measuring devicecomprises a dc accelerometer.
 4. A device as recited in claim 1, whereinsaid inclination measuring device comprises three accelerometersorthogonally mounted.
 5. A device as recited in claim 1, wherein saidinclination measuring device further comprises a magnetometer.
 6. Adevice as recited in claim 5, wherein said inclination measuring devicecomprises a plurality of magnetometers.
 7. A device as recited in claim1, wherein said magnetometer data is for providing direction withrespect to the earth's magnetic field.
 8. A device as recited in claim1, wherein data from said first sensor is subtracted from data from saidsecond sensor.
 9. A device as recited in claim 8, wherein saidsubtraction is to determine a difference in orientation.
 10. A device asrecited in claim 8, wherein said first sensor and said second sensor arefor measuring range of motion of said second body segment with respectto said first body segment.
 11. A device as recited in claim 10, whereinsaid range of motion measurement data is analyzed for change of range ofmotion over time.
 12. A device as recited in claim 11, wherein initialvalues of said time dependent data are tared out to provide change fromsaid initial values.
 13. A device as recited in claim 1, wherein saidstorage device comprises a solid state device.
 14. A device as recitedin claim 13, wherein said storage device comprises a non-volatile memorydevice.
 15. A device as recited in claim 1, further comprising afeedback mechanism
 16. A device as recited in claim 16, furthercomprising a housing, wherein said first sensor, said storage device,said processor, and said feedback mechanism are all within said housing.17. A device as recited in claim 15, further comprising a housingseparate from said first sensor and said second sensor, wherein saidfeedback mechanism is within said housing.
 18. A device as recited inclaim 17, wherein said first sensor and said second sensor arewirelessly connected to said housing containing said feedback mechanism.19. A device as recited in claim 18, wherein said wireless connection isan RF connection.
 20. A device as recited in claim 15, wherein saidfeedback mechanism is activated if a preset range of motion thresholdhas been exceeded too many times.
 21. A device as recited in claim 15,wherein said feedback mechanism provides vibratory or auditory feedback.22. A device as recited in claim 15, wherein said feedback mechanismcomprises a piezo-electric buzzer or an electromagnetic shaker.
 23. Adevice as recited in claim 15, wherein said feedback mechanism providesfeedback to warn of a problem, discourage a movement, support a desiredresult, or encourage a movement.
 24. A device as recited in claim 23,wherein said problem comprises repeatedly exceeding a pre-programmedinclination angle.
 25. A device as recited in claim 1, wherein saidprocessor comprises a microprocessor, a signal processor, or a personalcomputer.
 26. A device as recited in claim 1, wherein said datacomprises body segment orientation data as a function of time.
 27. Adevice as recited in claim 1, wherein said data comprises posture dataas a function of time.
 28. A device as recited in claim 1, wherein saiddata is used to adjust physical therapy.
 29. A device as recited inclaim 1, wherein said device further comprises a data entry system. 30.A device as recited in claim 29, wherein said data entry systemcomprises a button.
 31. A device as recited in claim 29, wherein saiddata entry system is for recording the presence of pain.
 32. A device asrecited in claim 29, wherein time, date or other data are recorded whensaid data entry system is used.
 33. A device as recited in claim 1,wherein said data is displayed as a histogram showing number ofinclinations at each angle range during a time period.
 34. A device asrecited in claim 1, wherein said data is displayed as inclination v.time.
 35. A device as recited in claim 1, further comprising a digitalfilter.
 36. A device as recited in claim 35, wherein said digital filteris for reducing effect of linear accelerations on the data.
 37. A deviceas recited in claim 35, wherein said digital filter comprises a low passfilter or a high pass filter.
 38. A device as recited in claim 1,further comprising a high pass filter, wherein output of saidaccelerometers that passes through said high pass filter is subsequentlyintegrated and used to compute a resultant velocity which is used tocalculate energy used.
 39. A device as recited in claim 1, wherein saiddevice is further for determining body posture in said sitting position.40. A device comprising a sensor, a processor, a storage device, and afeedback mechanism wherein data from said sensor is processed in saidprocessor to provide an output, wherein said output is stored in saidstorage device as a function of time, and wherein multiple points ofsaid time dependent output stored in said storage device are processedin said processor, wherein said processor directs said feedbackmechanism to provide information or instruction in response to saidmultiple points of time dependent output indicating too little activityor too small a range of motion of a joint during an interval of time, orrepetitive activity that can cause repetitive stress injury or too manymotions beyond a specified range of motion during an interval of time ortoo much vibration for too long a time.
 41. A device as recited in claim1, wherein said sensor comprises an inclination measuring device
 42. Adevice as recited in claim 41, wherein said inclination measuring devicecomprises a solid state device.
 43. A device as recited in claim 42,wherein said inclination measuring device comprises a dc accelerometer.44. A device as recited in claim 43, wherein said inclination measuringdevice comprises three accelerometers orthogonally mounted.
 45. A deviceas recited in claim 43, wherein said inclination measuring devicefurther comprises a magnetometer.
 46. A device as recited in claim 45,wherein said inclination measuring device comprises a plurality ofmagnetometers.
 47. A device as recited in claim 45, wherein saidmagnetometer is for providing direction with respect to the earth'smagnetic field.
 48. A device as recited in claim 40, further comprisinga network of said sensors.
 49. A device as recited in claim 48, whereina first sensor of said network of sensors is for placing on a first bodysegment and a second sensor of said network of sensors is for placing ona second body segment connected to said first body segment.
 50. A deviceas recited in claim 49, wherein output from said sensor is subtractedfrom data from said second sensor to provide angle of a joint therebetween.
 51. A device as recited in claim 49, wherein said first sensorand said second sensor are for measuring range of motion of said secondbody segment with respect to said first body segment.
 52. A device asrecited in claim 51, wherein said range of motion measurement data isanalyzed for change of range of motion over time.
 53. A device asrecited in claim 51, wherein an initial values of said time dependentdata is tared out for said first sensor and said second sensor toprovide change from said initial value.
 54. A device as recited in claim40, wherein said storage device comprises a solid state device.
 55. Adevice as recited in claim 54, wherein said storage device comprises anon-volatile memory device.
 56. A device as recited in claim 1, whereinsaid storage device and said processor are within the same housing. 57.A device as recited in claim 40, further comprising a housing, whereinsaid sensor, said storage device, said processor, and said feedbackmechanism are all within said housing.
 58. A device as recited in claim40, further comprising a housing separate from said sensor, wherein saidfeedback mechanism is within said separate housing.
 59. A device asrecited in claim 58, wherein said sensor is wirelessly connected to saidhousing containing said feedback mechanism.
 60. A device as recited inclaim 59, wherein said wireless connection is an RF connection.
 61. Adevice as recited in claim 40, wherein said feedback mechanism isactivated if a preset range of motion threshold has been exceeded morethan a specified number of times.
 62. A device as recited in claim 40,wherein said feedback mechanism provides vibratory or auditory feedback.63. A device as recited in claim 40, wherein said feedback mechanismcomprises a piezo-electric buzzer or an electromagnetic shaker.
 64. Adevice as recited in claim 40, wherein said feedback mechanism providesfeedback to warn of a problem, discourage a movement, support a desiredresult, or encourage a movement.
 65. A device as recited in claim 64,wherein said problem comprises repeatedly exceeding a pre-programmedinclination angle.
 66. A device as recited in claim 40, wherein saidprocessor comprises a microprocessor, a signal processor, or a personalcomputer.
 67. A device as recited in claim 40, wherein said outputcomprises body segment orientation data as a function of time.
 68. Adevice as recited in claim 40, wherein said output comprises posturedata as a function of time.
 69. A device as recited in claim 40, whereinsaid output is used to adjust physical therapy.
 70. A device as recitedin claim 40, wherein said device further comprises a data entry system.71. A device as recited in claim 70, wherein said data entry systemcomprises a button.
 72. A device as recited in claim 70, wherein saiddata entry system is for recording the presence of pain.
 73. A device asrecited in claim 70, wherein time, date or other data are recorded whensaid data entry system is used.
 74. A device as recited in claim 40,wherein said output is displayed as a histogram showing number ofinclinations at each angle range during a time period.
 75. A device asrecited in claim 40, wherein said output is displayed as inclination v.time.
 76. A device as recited in claim 40, further comprising a digitalfilter.
 77. A device as recited in claim 76, wherein said digital filteris for reducing effect of linear accelerations on the data.
 78. A deviceas recited in claim 76, wherein said digital filter comprises a low passfilter.
 79. A device as recited in claim 40, further comprising a highpass filter, wherein output of said accelerometers that passes throughsaid high pass filter is subsequently integrated and used to compute aresultant velocity which is used to calculate energy used.
 80. A deviceas recited in claim 40, wherein said device is further for determiningbody posture in said sitting position.
 81. A device as recited in claim40, wherein said device is wearable.
 82. A device as recited in claim40, wherein said device records output over a series of intervals oftime.